NL1024868C1 - Method and device for bringing parallel fibers to desired, mutually equal tension. - Google Patents

Description

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Method and device for bringing parallel fibers to desired, mutually equal tension.

5

The invention relates to a method and an apparatus for unwinding yarn reels, bobbins and spin cakes from a creel (rack with reels) and bringing these yarns to the correct mutual equal tension in order to feed them to a machine for further processing.

10

For the production of textile products, in particular the processing of high-quality industrial fibers such as glass fibers, aramid fibers and carbon fibers, it is important that the fiber tension in the end product is mutually equal. After all, during the manufacture of a semi-finished product or end product, the fibers were usually introduced with a certain prestressing force, which force after shrinkage of the product flows away. If the fibers had different diameters, as is often the case with spun yarns, the force flow away after the product has been produced leads to different shrinkage of the individual yarns, thereby adversely affecting the flatness of the product.

If the fibers are fixed during the process by impregnation with synthetic resin, as is customary in the manufacture of so-called prepregs, unidirectional material or tension-wrapping around a (temporary) bearing core, it may be advantageous to apply the fibers to a further to bring forward bias.

The correct and mutually equal fiber tension is of extreme importance if the tensile strength of the fibers is decisive for the proper functioning of the end product as is the case, for example, with wound plastic flywheels, high-pressure tanks and plastic rotors for fans and generators.

It is precisely these applications where the creel is directly linked to the device that takes care of processing the fibers into the end product or semi-finished product.

30

So far, dh is preferably carried out by providing each individual run-off point with an accurate (electronically controlled) brake that controls the run-off force.

1024868 .2

The braking of such a creel is more expensive the more the drop-off force of more down-points must be regulated. It should be noted that it is not possible to regulate the release voltage with this equipment but only the release force. Said braking is generally effected by measuring the deflection of a so-called dancer roller around which the fiber is guided and on the basis thereof strengthening or weakening the braking effect, so that only the force in the fiber is an indicator for controlling the brake · Only with very homogeneous fibers of the same diameter is the force in the fiber a measure of the tension in that fiber.

The present method does not have the abovementioned disadvantages of the prior art and can advantageously be used in situations where there is a need for pure voltage control, where many drain points are required simultaneously and with high accuracy, such as the manufacture of wide prepregs for the purpose of aircraft industry, the Printed-Circuit-Board manufacture and the manufacture of extremely lightweight sandwich panels. With a fiber bundle width of 1 mm, in that case 1,000 to 1,500 fiber bundles are not unusual.

The object of the present invention is to ensure in a simple and inexpensive manner that the fibers exported all have the same tensile stress within very narrow tolerances, irrespective of the varying random force with which they are introduced.

Although the invention is also suitable for transporting and tensioning and maintaining material with a more continuous structure such as a paper web, plastic web, composite material web or textile web, the invention will be further elucidated here on the basis of a preferred application in the field of fiber transport. explained.

SUMMARY OF THE INVENTION The method 5 Experiments have shown that the friction coefficient f exhibits greater constancy with sliding friction between a textile fiber and a roller surface than that with stationary friction. A small speed difference between fiber and drive roller therefore appears to have a stabilizing effect on the transmission of a constant drive force. With many material pairings this driving force is lower than the transmission 10 to be transmitted without any slip. Partly to avoid this phenomenon and to retain full grip, a so-called Anti-Locking System (ABS) has been developed for the automotive industry in order to be able to use the maximum braking power for as long as possible.

In the method according to the invention, it is precisely the object to limit the driving forces to a maximum level that can be compared with the same maximum level of adjacent fiber bundles. According to the theory of elasticity, it holds that mutually equal tension in warp threads or fibers of a prepreg or fabric can only arise with an equal elongation of those warp threads or fibers. According to that reasoning, if the passage of the end product via a roller with a peripheral speed V2 can take place slip-free and the supply of all warp threads can take place at a speed vi slip-free, the elongation between discharge and feed is the same for all warp threads. This reasoning applies equally to slippery rollers if vi is the speed of the fiber feed and V2 is the speed of the fiber feed. The speed of the rollers has thus become unimportant. The value of the elongation in that case is ε = (V2 -vi) / vi. The fact is that the product is discharged at the same speed along the discharge roller at each adjacent point of the circumference of that roller. We call this the production speed v2.

Thus, at each point of the circumference of that roller, a plane is conceivable which lies in the axis of rotation of that roller and which is also perpendicular to the cross-section of the product so that the condition of equal mutual speed is met.

1024868 4

The same mutual tension requires an equal predetermined elongation, so that at the front of the production process there must exist a section where all fibers are supplied at an equal speed vi.

Because transport of fibers by guiding them along a roller can only take place slip-free if the fiber tension before the roller and after leaving that roller is practically the same, the fiber tension is preferably built up from "zero" at least virtually zero.

This construction can, as is known, be realized by pulling the fibers over a number of stationary rods. This is described, for example, in the US patent US3253803. The build-up of the desired tension then takes place by encircling the rod according to the formula F2 = Fj * e * 0, where α is the angle through which the fibers covered the surface of the rod.

Because the coefficient of friction f is dependent on the material properties between the friction elements, here the fiber and rod surface, and can therefore be influenced to a limited extent, a higher desired friction can be obtained by increasing the enclosure angle α of the rod. In the present application, fiber bundles are situated next to each other, so that the circumference of the rod can only be used in a packaged manner.

The present invention therefore also encompasses increasing the clamped angle by the use of more rods whereby the fiber bundles can surround each rod to a maximum of almost 180 ".

A further improvement of the invention is achieved by rotating the rods in the conveying direction of the fibers at a peripheral speed that is marginally lower than the fiber speed.

Furthermore, the invention provides a method which makes it possible to reduce the tension of any fiber bundle tension to practically "zero".

This is possible with the aid of a device that is very similar to the method described above, on the understanding that the peripheral speed of the rollers in this case is marginally higher than the desired bundling speed. Such a method is described in the US patent USS9573S9 in which the voltage decreases due to the enclosure of one roller. Said patent makes use of the partial enclosure of only one roller over which the fibers slip so that the tensile force in the fibers is reduced so that a tensile force difference between the adjacent fibers of a maximum of approximately 100% can be equalized. In addition, by encircling a subsequent roller, it is assumed that the fibers would not slip over this latter roller due to a larger encircling thereof. This is at least doubtful because in case there is no slip of the fibers over this roller, the fibers would move along the roller along a helix. In any case, with this known device it is only possible to create a relatively very limited end voltage. In addition, this known device has the disadvantage that all fibers must be introduced manually over the set of rollers.

The present invention does not have these disadvantages because each fiber or bundle of fibers over the entire installation has, as it were, an own imaginary surface within which all the necessary operations take place. New is the idea that when using multiple rollers the tension in different fibers which at the start of the process have a possibly very greatly different value, regardless of the initial tension and the mutual difference, after a limited number of rollers and remaining within their own flat plane is reduced to a voltage level that is virtually zero. The voltage difference to be bridged, the desired accuracy, the coefficient of friction and the total encirclement determine the number of rollers. The number of fibers present at the same time in the process does not influence the operation, but only the total torque required and the strength of the structure. The invention is based on the fact that this stress reduction in the first part can be utilized by passing the fibers through the second part, a tension slot, from which in the third part they are brought to the desired and mutually equal tension over a number of rollers . The tension lock is constructed in such a way that the fibers cannot slip into the lock. Checking this tension can simply be carried out automatically by measuring the deflection of a measuring roller resting under bias, preferably perpendicular to the projecting fibers, and modifying the total encirclement of the rollers of the first processing phase in such a way that the deflection of the measuring roller returns to the desired position. The voltage difference for the lock, which is very small in an absolute sense, manifests itself on the other side of the lock as a very small speed difference. Because the initial speed before the third part is practically the same in all fibers, and the take-off speed for all fibers is mutually equal due to the nature of the subsequent process (for example a winding machine, an S-impregnation process or loom), the final tension in all fibers is also virtually the same. voltage lock is determined by the difference in tension at the start of the process, the number of rollers, the coefficient of friction f and the clamped angle α across all rollers and can therefore be reduced to a desirable minimum. with which for a large number of fibers from a random voltage level and random mutual voltage difference the voltage for all The fibers are simultaneously reduced to virtually stress-free, which is converted in the voltage slot to a substantially equal speed of the fibers. From the tension slot, in a known manner, by applying a speed difference, the tension can be increased for all fibers if desired. If it is not desired to increase the tension, it is possible for the follow-up process to cause the tension lock to be driven by the tensile force in the parallel fibers between the tension lock and the follow-up process. Also in that case the mutual voltage will not vary. Due to the equal elongation between the voltage lock and the place where the fibers become interconnected in the process following the device, the final tension is also very accurately the same for all fibers.

The invention also provides for an improvement of a tension lock by using an endless belt with elastomeric properties which is passed over a portion of the circumference of a roller. The fibers are pressed onto the roller by the belt, without many deformations occurring in the fibers, nor in the belt or the surface of the roller. The large surface makes it possible to exert a great frictional force on the fibers with a low surface pressure. The small deformations make it possible to guide the fibers through the lock without slip at a constant and known speed, the lock being little sensitive to the stresses present in the fibers.

1024840 »7

In summary, the method according to the invention consists of the following three processing phases: 1. Stress reduction of the fibers from any individual stress level to zero or substantially zero stress level.

2. Slip-free passage of the fibers through a tension lock with known, predetermined speed.

3. Mutual equal voltage build-up from voltage level zero to the desired collective voltage level.

This method ensures that all adjacent fiber bundles are brought from a random voltage level to a voltage level of zero or practically zero, whereby a new mutually identical voltage situation is realized and an identical throughput of the fiber bundles is obtained by means of a voltage slot. The build-up of the tension after the lock should take place gradually with the aid of a number of rollers which, as a result of a deliberate speed difference with the fiber bundles, dampen this until the correct tension is achieved. Because the path to be traveled is the same for all bundles, an identical elongation will occur, whereby an identical tension is guaranteed. The collectivity of treatment of the bed of fiber bundles naturally requires sufficient bending stiffness of the rollers. The diameter of these rollers is therefore advantageously not chosen to be too small. This also has the consequence that the bending stress of the individual fibers in the fiber bundles remains negligibly low so that fiber breakage in the device is excluded and the fiber ends themselves will simply be included in the fiber bundle package after any previous break and therefore no runners (rolling up individual fibers in a fiber bundle due to the frictional action of stationary guide elements).

1024868 8

The institution

The invention further comprises a device for performing the method described above. According to the invention, such a device is provided with a first part (relaxer) with at least one but preferably a number of cylindrical rotating elements (rollers), each roller of which can rotate about its own axis with a peripheral speed which according to a preferred embodiment is higher than the desired conveying speed at which the fibers to be transported are preferably looped around the rollers in order to realize an enclosure of these rollers whereby a greater total encircling angle can be achieved than would be possible with only one roller and a second part (voltage lock) with at least one wdls with a rigid, at least relatively non-deformable surface of which a part of the circumference exerts a frictional force on the intervening fibers by mating with a running pressure element consisting of an endless conveyor belt or a roller with compressible surface, so that these are slip-free with the peripheral speed v the roller with a stiff surface and thus determines the speed of the fiber throughput and a third part (tensioner) provided with rollers, whether or not rotating, around which the fibers are preferably pulled around in order to obtain a fiber tension build-up.

20

In order to guarantee the smooth operation of the release and the tensioner, it is important that the peripheral speed of the rollers of the release is always greater than the peripheral speed of the tension lock and the peripheral speed of the rollers of the tensioner at all times be smaller than the peripheral speed of the voltage slot.

This can be achieved in a simple manner by choosing the diameter of the rollers of the tensioner larger than that of the roller of the tension lock and the diameter of the rolls of the tensioner smaller than that of the roller of the tension lock and at the same time keep the speeds of all rollers the same.

In order to realize the proper operation of the device in a simple manner, it is preferably composed of two parallel frame plates interconnected with spacers and provided with a corresponding pattern of bearing points in which said rollers can be mounted.

1024368 »9 t

An embodiment with a particularly great ease of operation and suitable for a large diversity of frictional properties can be obtained by encircling a larger number of identical rollers, all odd rollers on a first frame part 5 being placed one above the other at a mutual distance that is more than twice the diameter of a roller and all even rollers on a second frame part are placed one above the other at the same mutual distance whereby approaching the first frame part through the second frame part allows the even rollers to pass spatially the odd rollers without touching each other in such a way that the rotation axes of all 10 rollers retain their mutual parallelism at all times.

With such an embodiment of the invention, maximum removal of the frame parts will result in a passage between the set of odd rolls and even rolls, whereby the one-time passage of fibers is greatly simplified. Approaching the first frame part through the second frame part will gradually result in an enclosure of all the rollers which can be raised by a further approach to a value determined by the product of the number of rollers and the half circumference of a roller.

The device also provides for reducing wear on the fiber and the device due to the continuous slip between the cylindrical elements and the fibers by driving the cylindrical elements from the third part of the device at a peripheral speed that is somewhat is lower than the desired fiber throughput.

25

Further wear can be advantageously avoided by providing the rollers with a wear-resistant layer obtained, for example, by surface hardening. An important positive consequence of the preferred embodiment according to the invention is also that due to the slip between the fiber bundles and roller surfaces a certain maximum friction can be transferred from the cylinder to the fiber bundle and therefore the value of the slip is unimportant for the proper functioning of the design. This means that the rollers which rotate slipping relative to the fiber bundles do not have to be completely round and can therefore be manufactured simply and inexpensively.

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Due to the freely selectable diameter of all rollers, the device, based on the preferred embodiment according to the invention, is insensitive to the occurrence of the previously explained runners and fiber breakage during passage of the device can be excluded.

The invention is then discussed with reference to the drawings. These drawings are merely illustrative of the present invention and are not to be construed as limiting.

10

Figure 1 shows a schematic representation of the physical principle on which the Invention is based;

Figure 2 shows a schematic representation of the entire device according to the essence of the invention; Figure 3 shows a schematic representation of the release and the tension lock according to the invention, wherein the device is in a position where bands, wires, filaments, fibers or bundles can be easily fed into the device; Figure 4 shows a schematic representation of the release and the tension lock according to the invention, wherein the two frame parts are moved towards each other relative to the position of Figure 3 and the tapes, wires, filaments, fibers or bundles abut a part of the circumference of the rollers;

Figure 5 shows a schematic representation of the release and the tension lock according to the invention, wherein the two frame parts are moved further towards each other with respect to the position of Figure 4 and the tapes, wires, filaments, fibers or bundles abut a larger one part of the circumference of the rollers;

Figure 6 shows a schematic representation of the tensioner according to the invention.

Figure 1 shows a fiber bundle that runs over a driven roller at a certain speed (v). The fiber bundle encircles the roller through an angle (a).

30 The roller rotates in the indicated direction with peripheral speed (ω * R). The coefficient of friction of the roller surface is (f). F1 is the tensile force in the fiber bundle in front of the roller. F2 is the tensile force in the fiber bundle after the roller.

1024868 11

Three situations can now occur: l 1. (<d * R)> v

The peripheral speed of the roller is greater than the speed of the fiber bundle. In this case the tension in the fiber bundle is reduced. Because the sliding friction is independent of the sliding speed, the speed difference between fiber and roller surface is not important. This situation occurs at the location of the release button.

(F1> F2).

2. (mxR) sv 10 The peripheral speed of the roller is equal to the speed of the fiber bundle. Slip-free transport of the fiber bundle now takes place. This situation occurs at the location of the voltage lock.

(F1 = F2).

3. (ω * R) <v 15 The peripheral speed of the roller is smaller than the speed of the fiber bundle. In this case the tension in the fiber bundle is built up. Here too, the speed difference does not affect the friction between the fiber and the roller surface. This situation occurs at the site of the tensioner.

(F1 <F2).

20

Figure 2 shows the way in which a single fiber coming from one of the run-off points (30i to 30iii) and located in the imaginary plane of the drawing undergoes all processing steps via a freely rotating roller (31) which serves to encircle all to make parallel fibers equal to the release device of the device. This is a first processing step by guiding the fiber over the rollers (16) and (5) alternately to the left and to the right, whereby due to the slip of the fiber relative to the roller circumference the force in the fiber is further reduced with each enclosure until a negligible strength remains. The sum of the remaining forces of all parallel fibers can be determined on the basis of a measuring roller 30 (32) which is pressed more or less perpendicular to the fibers projecting from the shutter-release to the voltage lock and the impression or the pressing force of which determines this remaining power.

1024868 »12

In the tension slot, the fibers are clamped between the roller (7) and the endless belt (11) such that the transport speed of all fibers is determined by the peripheral speed of roller (7). In a subsequent third processing step, the so-called tensioner, the same and desired tension is achieved by equal extension of all parallel fibers as a result of the fibers being rotated to the left and to the right with slip over a number of rollers (25) and (29). built up in all fibers. Said tensile force is supplied by the subsequent process, for example by a chain winder.

The final tension results in a sum of the forces of all fibers, which force 10 can easily be determined on the basis of a measuring roller (33) which is pressed more or less perpendicular to the fibers crossing from the tensioner to the subsequent process and whose impression or compression the compressive force determines this remaining force in the fibers.

Figure 3 is a schematic representation of the release and the tension lock in a position where the tapes, wires, filaments, fibers or bundles (12) can be easily passed through the device. The fibers (12) come from a stock (not shown) and are fed between the rollers (5,16). The fibers are then guided over a roller (7), the fibers being pressed onto the surface (8) of the roller by a belt (11). This interaction of roller (7) and belt (11) forms a tension lock. The belt (11) is tensioned by rollers (9).

The rollers (5) are journalled with frame part (1) and the rollers (16) are journalled with frame part (2). Both frame parts can move relative to each other, with a guide (3) allowing only one degree of freedom.

25

Figure 4 is a schematic representation of the release and the tension lock in a position where the bands, wires, fibers or bundles (12) are passed through the device and the frame parts (1,2) are approached to each other compared to the position of Figure 3 The fibers (12) now contact a portion of the surface (6, 17) of the rollers 30 (5, 16). The peripheral speed of the rollers (5.16) is higher than the fiber throughput, the arbitrary fiber bundle forces of the different discharge coils being reduced by the encircle of a first slipping rotating roller, which reduction is continued by successive slipping rotating rollers. in order to offer the fiber bundles with a minimum and negligible force level and therefore also a minimum and negligible mutual power difference between a precisely cylindrical rotating roller (7) with predetermined and constant circumferential speed on the one hand and an endless conveyor belt (11) with covering of sufficient sliding resistance material supported against it, on the other hand, whereby a non-slip drive of the fiber bundles (13), which has since been brought to very low tension, is obtained.

Figure 5 is a schematic representation of the release and the tension lock in the oath 10 position where the bands, wires, fibers or bundles (12) are passed through the device and the frame parts (1, 2) are closer to each other than the position from Figure 4. The fibers (12) now contact a larger portion of the surface (6, 17) of the rollers (5, 16). The tightened angle α of the fibers around the rollers has become larger, whereby more tension in the 1S fibers is reduced per roll, under the same conditions.

Figure 6 is a schematic representation of the tensioner wherein the tapes, wires, filaments, fibers or bundles (24) are in contact with a portion of the circumference (26) of rollers (25). The rollers have a circumferential speed which is lower than the feed speed of the fibers (24) whereby through each roll the tension in the fibers is increased according to the principle set out in figure 1. As a result of the equal elongation of the fibers between the slip-free supply and discharge over a uniform distance for all bundles, the tension of all fibers will be and remain the same. After all, where the stress is instantaneously higher, a momentarily higher elongation will occur, resulting in a lower normal force in the surrounding enclosure which immediately results in a decrease in friction and hence in the stress. The fibers (27) leave the device to to be further processed in a process that is not further shown. Also in this device the frame parts (21) and (22) can move relative to each other, with guide (23) allowing only one degree of freedom.

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Claims (14)

Method for bringing parallel fibers, threads, yarns and the like, further referred to as parallel fibers, from desired run-off points with unequal run-off force to desired, mutually equal or substantially the same tension, characterized in that the parallel fibers are first driven around one or more cylindrical, rotating elements (rollers) are guided, the circumferential speed of which is greater than the speed of the parallel fibers (Γ processing phase) such that at the end of the 1® processing phase the fiber tension is zero or practically zero and is then guided around a roller , Which transports the parallel fibers slip-free or almost slip-free (2® processing phase) and finally, if a higher tension is desired, guided around one or more stationary or driven rollers whose peripheral speed is smaller than the speed of the parallel fibers (3e processing phase) such that at the end of the 3rd processing phase the desired collective voltage is reached, Method according to claim 1), characterized in that a second roller is placed opposite the roller in the 2C processing phase between which pair of rollers the parallel fibers are guided. 20 Method according to claim 2, characterized in that the two rollers are pressed against each other with an adjustable force in the 2C processing phase. 4. Method according to any of claims 1) to 3), characterized in that the roller (s) are driven in the 2nd processing phase. 5. Method according to claim 1, characterized in that an endless belt is placed opposite the roller in the 2nd processing phase, which belt is positioned such that it surrounds part of the circumference of the roller placed opposite it. Method according to claim 5), characterized in that the roller and the endless belt are driven in the 2nd processing phase. 1024868 Method according to one of claims 1) to 6), characterized in that the parallel fibers are interconnected. « 8. Device for bringing parallel fibers, threads, yarns and the like, further referred to as parallel fibers, from desired run-off points with unequal run-off force to desired, mutually equal or substantially equal tension, characterized in that the device functions in accordance with the description in one of the preceding claims. Device as claimed in claim 81, characterized in that the part relating to the 1 * processing phase (relaxer) consists of two separate funnel parts (1) and (2), wherein on each frame part a number of driven rollers (5) and (16) are placed in line which can interlock in such a way that the surrounding of the parallel fibers around the roller surfaces (6) and (17) can be adjusted. Device as claimed in claim 81 or 91, characterized in that the part related to the 2® processing phase (tension lock) is formed by a driven roller (7) and an endless belt (11), driven by two drive rollers (9) wherein the roller (7) and the endless belt (11) can move toward each other such that the enclosure of the endless belt (11) around the roller surface (8) can be adjusted. 11. Device as claimed in any of the claims 8) to 10), characterized in that an element which is movable perpendicularly or substantially perpendicularly to the parallel fibers is placed between the relaxer and the tension lock, which element is in front of a force sensor. 12. Device as claimed in any of the claims 8) to 11), characterized in that the part with regard to the 3rd processing phase (tensioner) is designed in accordance with the release device as described in claim 9). 102468 Device as claimed in claim 12, characterized in that an element which is movable perpendicularly or substantially perpendicularly to the parallel fibers is provided immediately after the tensioner and which element is provided with a force sensor. 14. Method and / or device as described and / or explained with reference to the drawing. 1024888